1. Field of the Invention
This invention in general relates to electromagnetic launcher systems, and particularly to a system which has an augmenting field and allows for more efficient recovery of the post-firing barrel bore inductive energy.
2. Description of the Prior Art
Basically, in an electromagnetic launcher, a power supply supplies energy to two elongated, generally parallel electrodes called projectile rails, and between which there is a bridging electrically conducting armature freely movable along the rails. When a high current is commutated into the rails at the breech end, resulting magnetic forces propel the armature down the rails, and with it, a projectile which exits the far end of the rails, the muzzle end, at the desired high velocities. Alternatively, current conduction across the projectile rails may be provided by a plasma which accelerates the projectile assembly, which includes a sabot against which the high pressure and high temperature plasma exerts the accelerating force.
In one type of electromagnetic launcher to be described hereinafter, a high DC current source in the form of a homopolar generator is brought up to a predetermined rotational speed, at which time the kinetic energy of the homopolar generator is transferred to a storage inductor prior to being supplied to the rails for firing.
In one type of rapid or burst firing arrangement, a plurality of augmenting windings adjacent the rails carry current in the same direction as the rails thereby reducing the rail current necessary to attain a predetermined propelling force. Advantageously, a large magnitude of inductive energy remains in the rails after a firing and a fraction of this inductive energy can be transferred back to the augmenting windings to conserve energy expenditure per shot and to shorten the time necessary for the current to next attain a certain firing level, so that efficient rapid fire may be accomplished.
The augmenting windings also function as a storage inductance for the buildup of inductive energy prior to current commutation. The more augmentation windings provided, the greater will be the inductive storage capacity. In a typical system, however, each augmentation winding has a mass equal to or even greater than that of the rails. If the system has a rail length on the order of 10 meters, just 3 pairs of augmenting windings can add tons to the overall weight of the system. This additional weight severely hampers many tactical uses of the launcher.
The augmenting windings are physically adjacent the rails so that they link the bore magnetic flux. If the number of augmenting windings is reduced, to reduce weight, and if a separate storage inductor is provided to substitute for the lost inductive energy storage capacity, then the post-firing inductive energy storage transfer efficiency is severely degraded, since the separate storage inductor represents stray inductance not in a flux linking relationship with the other windings.
The present invention allows for significant weight reduction by providing an extraneous storage inductor in conjunction with a reduced number of augmenting windings while still retaining a high efficiency post-firing energy transfer.